Light emitting diode (LED) lighting solutions are replacing incandescent lighting and other less efficient solutions in a number of areas such as automotive headlamps. LEDs are more energy efficient, convert less energy to heat, and last much longer than incandescent bulbs. However, LED lighting solutions use more individual lighting elements than their incandescent counterparts.
LED lighting solutions typically arrange LED lighting elements into a matrix. Depending on the application, an LED matrix can be controlled using an integrated circuit that drives individual LED lighting elements. LED control is often achieved by commutating LED current through a parallel/bypass switch, a process commonly known as shunt or parallel switch dimming. Depending upon the required power/lumen output there can be multiple LEDs in series or parallel, fed by a current source or sink. In many cases, to achieve control of individual LEDs, each LED is bypassed by a switch and controlled using standard pulse width modulation (PWM) dimming techniques. When an overvoltage condition exists across a control switch, the control switch is closed to shunt the current that otherwise flowed through the LED. Large amounts of current flowing through the switch, however, can cause damage to and limit the longevity of a control device.